Esterastin is a known substance which has an esterase-inhibiting activity and which is recovered from the culture as obtained by cultivating a microorganism, Streptomyces lavendulae MD4-C1 (identified as FERM-P 3723 or ATCC. 31336). This microorganism was isolated from a soil sample collected in the ground of Biseibutsu Kagaku Kenkyu-sho in Shinagawa-ku, Tokyo, Japan. The production and the nature of esterastin is described, for example, in the "Journal of Antibotics" Vol. 31 No. 6 pages 639-641, U.S. patent application Ser. No. 873,350 and French patent application No. 78-04174. Esterastin is active to reduce the number of the cells forming humoral antibody and also to suppress the cell-mediated immunity. Esterastin is of a very low toxicity and may be used safely as a drug to chemotherapeutically treat diseases and disorders caused by the immune reactions such as contact allergic dermatitis, systemic lupus erythematosus,, autoimmune hemolytic anemia, periarteritis nodosa, myasthenia gravis, arthritis, rheumatism and multiple sclerosis. Furthermore, esterastin may be useful as an immunosuppressive drug in the surgical operations of transplantation of an internal organ such as heart, kidney and muscle. Esterastin is also expected to be useful as an anti-inflammatory agent because it inhibits the inflammation caused by carrageenin.
Esterastin has the following chemical structure ##STR1##
We, the present inventors, have made further research on esterastin and have now found that esterastin is catalytically reduced with hydrogen in the presence of a known hydrogenation catalyst such as platinum oxide or palladium to produce its tetrahydro derivative of the formula ##STR2## and that this tetrahydro derivative, now named tetrahydroesterastin is active to inhibit the action of esterase similarly to esterastin but exhibits a wider activity in that it inhibits a much larger number of enzymes than can be inhibited by esterastin.
Furthermore, we have now found that when esterastin is hydrolyzed under weakly alkaline conditions, for example, using 0.01 N aqueous solution of sodium hydroxide, there is produced one other esterase-inhibiting substance which is confirmed to be a new compound of the formula ##STR3## and which is now designated 3,5-di-hydroxy-2-hexylhexadeca-7,10-dienoic 1,3-lactone. Moreover, we have found that when tetrahydroesterastin is hydrolyzed under weakly alkaline conditions, for example, using 0.01 N aqueous solution of sodium hydroxide, there is formed another esterase-inhibiting substance which is confirmed to be a new compound of the formula ##STR4## and which is denominated 3,5-di-hydroxy-2-hexylhexadecanoic 1,3-lactone. It is also found that the latter compound may be produced also by catalytically hydrogenating the aforesaid 3,5-di-hydroxy-2-hexylhexadeca-7,10-dienoic 1,3-lactone in the presence of a known hydrogenation catalyst such as platinum oxide or palladium. These two, new compounds are also active to inhibit the action of esterase similarly to esterastin but have wider activity in that they inhibit a much larger number of enzymes than are inhibited by esterastin.